Metallic resistor for electric furnaces



June 21, 1932. T, BAiLY 1,864,334

METALLIC RESISTOR FOR ELECTRIC FURNACES Filed March 10. 1927 2Sheets-Sheet l T 17 Bang 33 June 21, 1932. T. F. BA ILY METALLICRESISTOR FOR ELECTRIC FURNACES 2 Sheets-Sheet 2 Filed Maren 10, 1927 T FBaily yzwm mama Patented June 213.1932

UNITED STATES ATE NT oF ica rmmmus r. BAILY, or unmet, 01110, assrenoaTo claim anaemic FURNACE comb rm, 011mm 01110, A qongona'rron' or 01110im'mnuomasrs'roaron ELEC'IBIO summons J) Application filed larch 10,1927. Serial No. 174,267.

The invention relates to resistor grids to be used in heating electricfurnaces and the like, and more particularly to a substantially.V-shaped, metallicresistor grid.

' In the past various forms of metallic resistors have been used in theform of wire, ribbon and cast grids. Inall such resistors, however, thecross sectional shape is such width to the widest portion thereof, isfaced toward the furnace wall. With such cross sectional shapes it willbeseen that a considerable portion of the heat which radiates from theresistor is thus directed toward the furnace wall. p

The object of the present invention is to provide a resistor grid ofsubstantially V;

shaped or Y-s'haped cross section, the apex of the .V being directed toone side of the plane of-the -grid so asto face the material to'beheated while the open side of the V is faced toward the furnace wall,thus minimiz-' ing the amount of heat radiated directly efliciency ofthe resistor grid.

An embodiment of the invention is illusagainst ,the furnace wall andincreasing the trated in the accompanying drawings, in which f Figure 1is a transverse verticalsectional view through a continuous sheetfurnace provided with the improved resistors;

1 Fig. 2, a fragmentary plan sectional view on the line 22, Fig. 1;'Fi'g. 3, a fragmentary loiiigitudinal sectional view on the line 3 3, 1ig. 1;

' Fi 4, a transverse sectional view through oneorm of the resistor,showing the same mation of the resistor;

I and formed froma plate or heavy sheet;

Fig. 5, a similar view showing another for- 6, a cross sectional-viewthrough a Fig. 7, a fragmentary plan view showing one form of endconnection for the resistor,

Fi 8, an enlarged section on the 'line 8f -8,

Fi v I gimilar numerals'refer to similar parts throughout the drawings.

The invention consists primarily in the revision of a sinuous metallicresistor I ormed of a plurality of spaced parallel bars" 1, of suitableheat resisting alloy, which may be connected together at alternate ends- 'to provide a continuous resistor grid.

" The cross sectional shape of these straight bars is substantiallyV-shape, and the bars maybe formed from heavy sheets or plates or rolledshapes, of heat' resisting alloy and the sides slightly concaved as bestshown at tened end portions being welded together at their longitudinaledges.

If desired, a separate connecting member may be provided, as shown inFigs. 7 and 8, in which-the substantially U-shaped connect- '60 '2 inFigs. 5 and 8, .or if desired, the sides ing member 5 is used to connectadjacent ends of the bars together.

This connecting member has the flattened central portion 6' and thesubstantially V'- shaped legs 7 which extend into the open ends of thestraight bars 2, being welded thereto at the upper edges as indicated at8.

Ifdesired, the entire resistor may be cast in a single piece bent uponitself to form-a grid including a plurality of parallel straight barsconnected at alternate ends by curved portions, each straight bar oftheresistor being of substantially the cross sectional shape shown at 9 inFig. 6, and having the concave sides 10 and the V-shapedrecess 11 in itsrear or outer side.

It will be noted that the efi'ect of concaving or depressing the sides10 of the V-section is to reduce the thickness and consequently the massof metal at the junction of the sidewalls of the V; with the result thatthere isless difference in the thickness of the metal at the junction ofthe walls, as'compared with the thickness of the walls themselves and ofthe elongated apex of the V.

A substantial uniformity in the thickness of the section is veryimportant in the casting ofthe metals usually employed for resistance'grids; because the shrinkage of such metals, when cooling from themolten state, is large, and tends to produce shrinkage'cavities in anyportion of the casting which cools at a much slower rate than the otherportion.

The exact contour of the side walls 10 of the V, will depend largelyupon the angle of divergence, and the extent to which the apex iselongated from a true V to what might well be called a Y-section, asshown in Fig. 6; but in any event, there should be maintained asubstantial uniformity in the thickness of the metal.

In applying the resistors to a continuous sheetfurnace such asillustrated generally at 12 in Figs. 1 to 3 inclusive, one of theresistors may be located adjacent to and upon each side of the path ofthe sheets 13, the apex of each straight bar of each resistor facingtoward the sheets as best shown in Fig. 3.

Grooves 14 may be formed in the side walls of the furnace to receive theconnecting portions of the resistors, and hooks or hangers 15 arepreferably located in the side walls of the furnace and extend into saidgroovesto support the resistors.

As best shown in Fig. 2, the connector portion 4 of the resistors restupon the hangers 15, the hangers extending between the ad-' jacentstraight bars 1 of the resistor.

This provides for sliding movement of the resistor upon the hangers toaccommodate expansion and contraction of the resistors and at the sametime the turned up portion 16 of the hanger keeps the straight bars ofthe resistor properly spaced.

From the above description and the illustration in the accompanyingdrawings, it will be seen that a hollow' V-shapedresistor is providedinwhich the apex of the resistor faces toward the work while the open sideof the resistor is faced toward the adjacent furnace wall, thusdisposing the greater portion of the cross section of the resistortoward the work. i

It will also be seen that the cross sectional shape of the resistor issuch that the depth is considerably greater than the width, and thedepth of its side walls is many times greater than the thicknessthereof. I

It will be noted that the resistor is of such section and so disposedwith referenceto the work that substantially all of the resistor sectionis beyond the line of its base and facing the work; and because the sidewalls are inclined at a substantial angle from the axis of the V, all ofthe direct radiation from the gridis in a direction toward one side ofthe plane of the grid.

I claim:

'1. A metallic resistor of substantially V- shaped cross section, havingsides of less thickness than their depth and an elongated apex, andhaving the side faces depressed to decrease the difference in thethickness of the metal in the sides and in the elon ated apex, ascompared with the metal at the ]l1I1C- 3. A sinuous metallic resistorgrid of open V-shaped cross section, the side walls being inclined at asubstantial angle from the axis of the V and their depth being manytimes greater than the thickness thereof, the apex of the V beingdirected to one side of the plane of the grid.

4. A sinuous metallic resistor grid of open V-shaped cross section,having its sides deeper than the width of its base, and the side wallsbeing inclined at a substantial angle from the axis of the V and theirdepth being many times the thickness thereof, the apex of the V beingdirected tov one side of the plane of the grid. i

5. A sinuous metallic resistor grid of open V-shaped cross section,having its sides con-' caved, and the side walls being inclined at asubstantial angle from the axis of the V and their depth being manytimes the thickness thereof, the apex of the V being directed to oneside of the plane of the grid.

6. A metallic resistor grid including a sgraight bar of substantially Ycross sectional s a e.

7. A metallic resistor grid including a straight bar of substantially Ycross sectional shape, each rib of the grid being tapered toward itsouter edge.

'8. A metallic resistor grid formed of a bar of Y cross sectional shapebent upon itself to provide a plurality .of parallel portions connectedat alternate ends by curved por-' tions.

9. A metallic resistor grid including a plurality of straight bars of Ycross sectional shape connected at their ends to produce a sinuous grid.

10. A sinuous metallic resistor grid having a substantially Y crosssectional shape. "In testimony that I claim the above, I have hereuntosubscribed my name. I

THADDEUS F. BAILY.

